The present invention relates to a press machine stroke operation mechanism comprising a servo motor and a link mechanism, and a method of controlling the position and speed of the stroke operation of the mechanism so that the press machine is operated in accordance with the working contents of the intended press work.
Press machines using a servo motor as a driving source of a stroke operation mechanism are proposed in Japanese Patent Laid-Open Nos. 62-252700, 62-296999 and 62-297000. A press machine using a link mechanism as a stroke operation mechanism is also known as a quick-return press or the like.
However, the previously proposed press machines using a servo motor as a driving source are screw presses and are developed as single purpose machines for caulking. Thus such press machines are not intended to be used considering the pressure applied to a workpiece, the pressure speed or a position in a stroke where the pressure and speed are applied.
Since the link mechanism of the known link press is also incorporated into a machine in order to simply quickly return a slide member, the same press mechanism cannot be used for press works having different work contents.
However, if the way of applying the pressure and the pressure speed to a workpiece can be changed for working different workpieces by a single press machine, press machine makers need not to produce different machines according to work contents, and the user also need not to buy and install machines respectively required for different work contents. It is thus thought that an attempt can be made to significantly rationalize the press work from various viewpoints.